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from __future__ import print_function, unicode_literals, absolute_import, division
class Tableau(object):
def __init__(self):
# Map of variable to set of variables
self.columns = {}
# Map of variable to LinearExpression
self.rows = {}
# Set of Variables
self.infeasible_rows = set()
# Set of Variables
self.external_rows = set()
# Set of Variables.
self.external_parametric_vars = set()
def __repr__(self):
parts = []
parts.append('Tableau info:')
parts.append('Rows: %s (= %s constraints)' % (len(self.rows), len(self.rows) - 1))
parts.append('Columns: %s' % len(self.columns))
parts.append('Infeasible rows: %s' % len(self.infeasible_rows))
parts.append('External basic variables: %s' % len(self.external_rows))
parts.append('External parametric variables: %s' % len(self.external_parametric_vars))
return '\n'.join(parts)
def note_removed_variable(self, var, subject):
if subject:
self.columns[var].remove(subject)
def note_added_variable(self, var, subject):
if subject:
self.columns.setdefault(var, set()).add(subject)
def add_row(self, var, expr):
# print('add_row', var, expr)
self.rows[var] = expr
for clv in expr.terms:
self.columns.setdefault(clv, set()).add(var)
if clv.is_external:
self.external_parametric_vars.add(clv)
if var.is_external:
self.external_rows.add(var)
# print(self)
def remove_column(self, var):
rows = self.columns.pop(var, None)
if rows:
for clv in rows:
expr = self.rows[clv]
expr.remove_variable(var)
if var.is_external:
try:
self.external_rows.remove(var)
except KeyError:
pass
try:
self.external_parametric_vars.remove(var)
except KeyError:
pass
def remove_row(self, var):
# print("remove_row", var)
expr = self.rows.pop(var)
for clv in expr.terms.keys():
varset = self.columns[clv]
if varset:
# print("removing from varset", var)
varset.remove(var)
try:
self.infeasible_rows.remove(var)
except KeyError:
pass
if var.is_external:
try:
self.external_rows.remove(var)
except KeyError:
pass
# print("remove_row returning", expr)
return expr
def substitute_out(self, oldVar, expr):
varset = self.columns[oldVar]
for v in varset:
row = self.rows[v]
row.substitute_out(oldVar, expr, v, self)
if v.is_restricted and row.constant < 0.0:
self.infeasible_rows.add(v)
if oldVar.is_external:
self.external_rows.add(oldVar)
try:
self.external_parametric_vars.remove(oldVar)
except KeyError:
pass
del self.columns[oldVar]
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